RE: dirt in carb
Try NOT to rotate the prop (if there IS dirt inside, it could get between the parts and start grinding away).
Unscrew the backplate, remove it (watch out for the gasket, its fragile) and the gasket.
Get your hot water tap running and get it as hot as you can. Then let the water flow through the open carb through the engine out the back. Gently rotate the prop so the piston allows free water flow through the engine.
Don't worry about water in the engine. The castor in your fuel will protect all surfaces. Then you can take your heat gun (or even a hair dryer) and dry all the surfaces (in and out) that you can see.
Put the back plate/gasket back on (carefully) and retighten the bolts (in an X pattern--just like you alternately tighten wheel bolts on your car tires). Put the now complete engine back on your plane, fuel up and go fly.
No problemo. Happens to me quite often and never a problem after this type of cleaning.